| 摘要 |
PROBLEM TO BE SOLVED: To provide a crime preventing sensor device capable of keeping a light reception level of a light receiver proper without receiving influence of external environment or restriction of an installation place to prevent report failure or a false report, and improving detection accuracy of the light reception level. SOLUTION: In this crime preventing sensor device, because changing a proper range of the light reception level according to temporal fluctuation of the light reception level, and adjusting a light projection amount from a light projector 11 such that the light reception level comes in the proper range when the light reception level comes out of the proper range, the light reception level comes in the proper range changed according to a change of the external environment even if the external environment changes, so that the light reception level can be kept proper always in operation of the device without receiving the influence of the external environment or the restriction of the installation place to prevent the report failure or the false report. Because the adjustment of the light projection amount reduces a peak value of the light reception level, a dynamic range of an A/D converter 26 can be increased as the result, so that resolution is increased to improve the detection accuracy of the light reception level. COPYRIGHT: (C)2006,JPO&NCIPI |
